By our third year of medical school, we’d all been lied to by our patients. Do you smoke? Do you eat salt? Are you sexually active? Do you use cocaine?

The late Dr. J.J. Smith, my OB-GYN professor, taught us that sometimes it wasn’t that patients were lying, but that they didn’t understand. He talked about a patient who, when asked if she was sexually active, said “no” even though the medical student treating her later got back a positive on her pregnancy test.

“I thought you said you weren’t sexually active,” the student said.

“But I’m not. He’s the active one,” she answered.

In residency, we used an “admitted:actual” drinking ratio. At the Denver VA hospital, the lying ratio was 1:2, wherein for every drink the patient admitted to consuming, you multiply by two to get the real number. The University Hospital had a ratio of 1:3. Denver General Hospital had a ratio of 1:1, not because they drank less (they actually drank more); these inner city drinkers just didn’t bother to lie about it.

“I don’t eat anything, and I’m so overweight” is something I hear a lot. I suppose that there are allowances for metabolism and that some people are just genetically bigger. Still, my Dad once asked the following to an overweight aunt who made a similar claim: “Remember when we were kids in Italy? During the war?”

“Of course I do,” she said.

“Do you remember seeing anybody who was fat back then?” he asked.

“Of course not,” she said. “ There was nothing to eat back then.”

Sometimes people lie and it seems to make no sense. One guy lied and said he smoked cocaine but never injected it. He later admitted to injecting and said he was embarrassed because, to him, injecting proved he was an addict. Another gal said the reverse. She admitted to injecting cocaine but said she’d never be one of those girls who smoke crack (even though she later admitted to doing it). Understanding the different stigma attached with shooting or smoking is a whole other experience than what I have.

Patients with severe heart failure can die from too much salt, and they know it. And yet they still eat hot dogs, Kung Pao Chicken and Pringles. They then deny that they have consumed any salt. Willful ignorance? Denial? What really matters is that they learn how not to eat salty foods.

Maybe it’s just that people only remember what they want to, like how I remember only the good shots I had in tennis but conveniently forget those easy ones I messed up. I go away thinking I’m a much better tennis player than I really am. I’m not really lying willfully, but I’m selectively remembering. Women during the labor of childbirth swear they will never get pregnant again, but then swear later that they never said any such thing.

I don’t think people are actually telling lies as much as they are reinventing the ideal of who they want to be. One of my favorite things about being a doctor is when patients realize that any shame or stigma attached to the truth is much less important than getting to the elusive truth in order to solve the problem.